Composition and method for producing smoke



United States Patent 3,309,268 COMPOSITION AND METHOD FOR PRODUCING SMOKE Louis M. Sherman, Ocean City, N.J., assignor to the United States of America as represented by the Secretary of the Army No Drawing. Filed Dec. 16, 1964, Ser. No. 413,928

2 Claims. (Cl. 167-39) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

The principal feature of this invention is to enhance the volatility rate of a vaporizable material by incorporating therewith an organometallic compound.

Heretofore in the conception, preparation and application of materials to produce obscuring, marking, signal and other purpose smokes for use by the military services, and for other uses, such as riots, insurgency, counter insurgency, etc., has been directed toward obtaining chemical mixtures, liquid or solid, which would produce smoke, regardless to the smokes toxicity, corrosiveness or irritability, eithter by exposure to the atmosphere resulting in reaction of the mixture with the moisture in the atmosphere, or pyrophoric means. Personnel anticipating exposure to smokes produced from existing, liquid and solid mixes, must wear protective clothing and/or protective breathing equipment due to the hazardous nature of the present smoke agents now employed. Such protective clothing is costly, reduces personnel efliciency and presents logistical problems.

For certain tactical operations by the Armed Services, allies, friendly or neutral personnel, law enforcement agencies e-tc., noncorrosive, nonirritant, nontoxic, non inflammable obscuring smokes are desired. Such relatively harmless smokes are urgently needed for reasons related to political science, namely in the areas of the world where ideologies are in armed conflict and we have a desire for the active support of the people every effort must be made to minimize civilian casualties from hazardous smoke or fumes and/or damage to their possessions from pyrophoric materials.

For this reason various methods have been employed to generate non-hazardous smokes from petroleum oils using heat sources, such as gasoline turbine engines, reciprocating diesel and gasoline engines, hot exhaust gases and other heat sources. In addition, fog generating apparatus, using water and chemicals, such as higher molecular weight alcohols, with or without heat sources, have been tried. However, the use of oil, or water, have necessitated heavy and bulky ancillary equipment, namely heat sources and/ or pressure equipment, which often is impractical to use in aerial and/or jungle and other tactical operations.

It is the object of this invention to produce an improved obscuring smoke either of a nontoxic or toxic variety.

Such an object is accomplished by utilizing a composition of matter consisting of an organometallic chemical and smoke oil or hydrocarbons and hydrocarbon derivatives. The smoke oil may contain aliphatic hydrocarbons or aromatic hydrocarbons, a mixture of the two, or

silicone, fiuorocarbons, etc. To this, other substances may be added to meet the need of special circumstances, such as a mixture to prevent freezing, reduce flame hazard, improve stability, minimize corrosive characteristics, improve solubility or miscibilities, etc.

3,309,258 Patented Mar. 14, 1967 Present smoke agents FS (sulphur trioxide-chlorosulphonic acid) and FM (titanium tetrachloride) which depend upon the reaction of the moisture in the atmosphere, vary markedly in efficiency and quantity of smoke produced with the humidity of the atmosphere. On the other hand, organometallic chemicals react with oxygen in the atmosphere and the proportion of oxygen in the atmosphere is very nearly constant over the earth. Therefore, a more constant smoke producing capability is anticipated per unit weight of the mixture containing organometallic compounds.

One example of an organometallic compound for this invention is 25% by weight of diethylzinc in a smoke oil such as heptane, or 50% by weight of dibutylzinc in heptane which may be exposed to atmosphere to produce the smoke desired. A flame inhibitor may be used if necessary to prevent the reaction reaching the flash point of the smoke oil. As an alternative the organometallic compound may be immersed in a silicone which is flash proof and removes the necessity of adding a flame inhibitor and therefore performs a dual function. The organometallic compound may also be immersed in a fluorocarbon which is also flash proof and removes the necessity of adding a flame inhibitor and likewise performs a dual function. Once air starts the reaction, the exothermic nature of the oxidation of the organome-tallic compound hastens the generation of smoke so that a greater volume of smoke is produced in a shorter period without reaching the flash point of the smoke oil.

In view of this a general formula for the smoke agent is as follows:

Percent Organometallic 5-50 Oil 5-95 Other 0-80 Another sepecific mixture that produces a good nonhazardous smoke is as follows:

Comparisons of the quantity of smoke produced by mixtures containing organometallic compounds and the usual smoke agents, such as, FM (titanium tetrachloride) and .FS (sulphur trioxide-chlorosulphonic acid) indicate that, on a weight basis, as much or more, smoke is obtained per unit weight with the mixtures containing the organometallic compounds.

While the motivation of this invention is generally for the production of nontoxic, noncorrosive, nonirritating, noninflammable obscuring smokes produced by organometallic chemicals of zinc, magnesium, aluminum, tit anium, zirconium, manganese, tin and others; but it should be noted that there are other organometallic compounds which are equally effective in the production of toxic and irritating smokes and fumes which utilize the metals of lithium, other alkali metals, boron, mercury, beryllium, and other mixtures of these organometallic compounds with obnoxious, irritating, toxic, destructive chemical additives, with or without oil and other chemicals.

It is also noted that with suitable ingredients in the mixture that smoke, or fumes, so produced can serve as insecticides, miticides and for other fumigation purposes, such as preservation or deterioration of food and other material.

Also, the obscuring smoke may be colored by the addition of an inert, soluble or insoluble coloring constituent such as dyes, pigments, metals, and organic or inorganic compounds to the composition of the smoke agent.

What is claimed is:

1. -An obscuring smoke agent for the production of a smoke screen in which the smoke agent consists essentially of 4050% by Weight of triethyl aluminum and 60-50% by Weight of smoke oil and the evolved smoke being nontoxic, noncorrosive and nonirritating.

2. A method of producing a high volume of obscuring smoke which comprises, mixing triethyl aluminum with a smoke oil and heating the mixture for the initial production of smoke where the reaction of triethyl aluminum with oxygen from the atmosphere results in an increased production of smoke only by the additional heat generatcd in the exothermic reaction and a greater volume of smoke is generated in a shorter period of time.

References Cited by the Examiner UNITED STATES PATENTS 2,151,432 3/1939 Lyons 4468 2,408,429 10/1946 Levey 252-305 3,082,234 3/ 1963 Kitasaki 44--68 OTHER REFERENCES Hatch: Chem. Abstracts, 44 (1950). Dumez: Chem. Abstracts, 50 (1956). 

2. A METHOD OF PRODUCING A HIGH VOLUME OF OBSCURING SMOKE WHICH COMPRISES, MIXING TRIETHYL ALUMINUM WITH A SMOKE OIL AND HEATING THE MIXTURE FOR THE INITIAL PRODUCTION OF SMOKE WHERE THE REACTION OF TRIETHYL ALUMINUM WITH OXYGEN FROM THE ATMOSPHERE RESULTS IN AN INCREASED PRODUCTION OF SMOKE ONLY BY THE ADDITIONAL HEAT GENERATED IN THE EXOTHERMIC REACTION AND A GREATER VOLUME OF SMOKE IS GENERATED IN A SHORTER PERIOD OF TIME. 